It would help to know what your budget amount is because there are some very good 560Ti's out there including the just released 448 core. If you are looking to get something that will give you good fps in BF3;
EVGA 012-P3-2066-KR GeForce GTX 560 Ti (Fermi) 448 Cores FTW 1280MB 320-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
$289.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130738
Astandard 560Ti has 384 proccessor cores and this one bumps it up to 448 which translates into better performance , while you still will not be able to max out on ultra you may be able to play at those settings and get playable fps. It would be better to play at the high settings and get more fps then to try and play at ultra. But like I said I don't know what you are willing to spend so this is just a guess. If this is too high then a regular 560Ti might be more affordable for you.
EVGA SuperClocked 01G-P3-1563-AR GeForce GTX 560 Ti (Fermi) 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
$239.99 and a $20 rebate makes it $219.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130610
A 560Ti has 384 proccessor cores vs a 560 which has 336 and again the more proccessor cores the better the perfomance , and the higher the price.
EVGA SuperClocked 01G-P3-1463-KR GeForce GTX 560 (Fermi) 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card
$199.99 and a $20 rebate makes it $179.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130664